Mowing machine with annular inertia shifter

ABSTRACT

A mowing machine is provided with its cutting head employing one or more flexible cutting lines such as Nylon cords which serve to cut grasses during rotation of the cutting head. The free end portions of the cutting lines extend radially outwardly from a casing through openings in an annular inertai shifter which is housed in the casing for vertical and angular movements relative to the casing.

The present invention relates to mowing machines employing one or moreflexible cutting lines such as Nylon cords as cutting blades.

In such mowing machines, flexible cutting lines are housed in the formof coils in a casing and have free end portions extending radiallyoutwardly through openings formed in the casing as its periphery. Duringmowing operation, the free end portions of the cutting lines arestretched radially outwardly of the casing under the action of thecentrifugal force to cut grasses. As compared with steel cutting bladesin a conventional mowing machine, the flexible cutting lines are liableto wear off during the mowing operation. When the free end portions ofthe cutting lines have worn off, there is a need for extraction of thecutting lines from their coils through the openings. In order to ensurethat such an extraction operation can be performed without any stoppageof a motor, there have been known semiautomatic feeders comprising ashifter serving to extruct the cutting lines and adapted to be operatedby a change in the centrifugal force caused by a variation in rotationalspeed of the mowing machine head or by applying to the shifter anexternal force caused by striking the mowing machine head against theground.

A main object of the present invention is to provide a mowing machinewhich is capable of extraction of the cutting lines from their coilsthrough a casing means of a cutting head during a mowing operationwithout varying the rotational speed of the cutting head or striking itagainst the ground.

Another object of the present invention is to provide a mowing machinewherein an annular inertia shifter is disposed in the casing of thecutting head for vertical and angular movements relative to the casing.The annular shifter is provided with openings through which the free endportions of the cutting lines extend radially outwardly and when themowing machine is swung vertically during its operation to movevertically the inertia shifter relative to the casing, the inertiashifter is angularly moved relative to the casing under the action ofthe centrifugal force on the free end portions of the cutting lines toextract the cutting lines from their coils through the openings in theshifter a predetermined length.

In a preferred embodiment of the present invention, the cutting linesare wound around a spool fixedly secured within the casing means. Thecasing means includes casing and a cap defining an annular spacetherebetween. The inertia shifter surrounds the spool within the casingmeans and has openings formed in the portion of the shifter which isexposed to the annular space. The inertia shifter is provided with aplurality of upper circumferentially spaced projections formed thereonand adapted to engage a plurality of circumferentially spacedprojections on the casing during mowing operation of the machine. Aplurality of lower circumferentially spaced projections may be formed onthe shifter in an opposite relation to the upper projections to engageprojections each formed on the cap at a position intermediate betweenthe two adjacent projections on the casing so as to being capable ofextracting the cutting lines a predetermined length on halves.

Other objects and advantages of the present invention will becomeapparent from the following description on a preferred embodimentthereof which is shown in the accompanying drawings;

FIG. 1 is a perspective view of a mowing machine according to thepresent invention;

FIG. 2 is a vertical cross sectional view of a cutting head of th mowingmachine shown in FIG. 1;

FIG. 3 is a cross sectional view of the cutting head taken along lineIII--III of FIG. 2;

FIG. 4 is a fragmental cross-sectional view of the cutting head takenalong line IV--IV of FIG. 3; and

FIG. 5 is a perspective view of an inertia shifter housed in the cuttinghead.

Referring now to FIG. 1 of the drawings, there is shown a mowing machineaccording to the present invention comprising a rotary cutting head 3rotatably mounted on a hallow rod 2 at its lower end. The hollow rod 2has a small internal combustion engine 4 mounted at the upper endthereof and is provided with a flexible driving shaft 1 extending fromthe engine 4 to the rotary cutting head 3 and inserted in the hollow rod2. Referring now to FIG. 2, the rotary cutting head 3 comprises acup-shaped casing 5' having a central boss 8 fixedly secured thereto andthreadedly connected to the lower end of the flexible driging shaft 1, aspool 10 fitted on the boss 8 and a cap 5 fitted on the boss 8 andlocked to the cup-shaped casing 5' by a nut 9 which threadedly engagesthe lower threaded end of the boss 8 to clamp the spool 10 between thecasing 5' and the cap 5 for rotation therewith. The spool 10 hasflexible cutting lines 11, such as Nylon cords wound thereon in adirection opposite to a direction of rotation of the cutting head 3.Defined between the casing 5' and the cap 5 is an annular space 6through which the free end portions 7 of the cutting lines 11 extendradially outwardly.

An annular inertia shifter 12 is mounted within the casing 5' forvertical and angular movements relative to the casing 5' and providedwith a plurality of upper and lower circumferentially equally spacedprojections 14 and 15 oppositely formed on the upper and lower endsthereof. The casing 5' and the cap 5 are also provided with a pluralityof circumferentially equally spaced projections 16 and 17 cooperatingwith the upper and lower projections 14 and 15 on the inertia shifter12, respectively. Each of the projections 17 on the cap 5 is positionedintermediate the two adjecent projections 16 on the casing 5'. Formed inthe portion of the inertia shifter 12 which is exposed to the annularspace 6 between the casing 5' and the cap 5, are two diametricallyopposite openings 13 each positioned intermediate the opposite upper andlower projections 14 and 15 on the inertia shifter 12. Each of theopenings 13 serves to bear the free end portion 7 of the cutting line 11passed therethrough and preferably, has a curved convex surface insection to avoid any concentration of stress on the cutting line. Theopenings 13 may be in the form of slots opening into the upper end orlower end of the inertia shifter 12.

During rotation of the rotary cutting head 3, the inertia shifter 12 ispositioned in the casing 5' with the leading edge of each of theprojections 14 engaging the trailing edge of each of the projections 16on the casing 5'. This is achieved by winding the cutting lines 11 onthe spool 10 in the direction opposite to the direction of rotation ofthe rotary cutting head 3 and by the centrifugal force acting on thefree end portions of the cutting lines passed through the openings 13 inthe inertia shifter 12 to tend to forwardly rotate the inertia shifter12 relative to the casing 5' until the leading edge of each projection14 on the shifter 12 engages the trailing edge of the projection 16 onthe casing 5'.

During the mowing operation, it is necessary to maintain the inertiashifter 12 at its lifted position where the projections 14 on theshifter 12 engage the projections 16 on the casing 5' in order toprevent downward movement and subsequent rotation of the inertia shifter12 relative to the casing 5', which would result in an unforeseenextraction of the cutting lines from their spool 10 through the openings13 in the shifter 12. To this end, each of the openings 13 is positionedsuch that when the inertia shifter 12 is in its lifted position wherethe upper projections 14 on the shiftes 12 engage the projections 16 onthe casing 5', the top 19 of the curved surface of the opening 13 shouldbe spaced axially from the inner surface 18 of the lower one of thespool flanges a distance slightly less than a diameter of the cuttingline 11 extending through the opening 13 to bend it downwardly. Duringthe rotation of the rotary cutting head 3, the downwardly bent portionsof the cutting lines have a tendency to be stretched outwardly due tothe centrifugal force acting on the free end portions of the cuttinglines so that the tension on the cutting lines causes the shifter 12 topush up thereby maintaining engagement of its projections 14 with theprojections 16 on the casing 5'. Alternatively, in order to achieve thedownward bending of the cutting lines, barrier rings (not shown) mayextend upwardly from the cap 5 so as to surround the periphery of thespool 10.

In operation, the internal combustion engine 4 is started to rotate theflexible driving shaft 1 so that the casing 5' and cap 5 of the cuttinghead 3 rotate with the spool 10 fixedly secured therewithin. Thecentrifugal force causes the free end portions of the cutting lines 11passed through the openings 13 to stretch radially outwardly, therebylifting and rotating the inertia shifter 12 relative to the casing 5' inits direction of rotation until the leading edges of the projections 14on the shifter 12 engage the trailing edges of the projections 16 on thecasing 5' (see FIG. 3). During the mowing operation, the shifter 12 isrotated in the direction opposite to the direction of the rotation ofthe cutting head 3 at the time when the free end portions of the cuttinglines 11 hit the grasses so that each of the projections 14 on theshifter 12 circumferentially oscillates between the two adjacentprojections 16 and 16 on the casing 5'. Because of the oscillation ofthe projections 14 on the shifter 12, a point of contact of the free endportions of the cutting line 11 with the openings 13 moves along thelength of cutting lines to minimize the chances of their breakage.

When the tip of each of the free end portions of the cutting lines 11has worn off and it is desired to extract the free end portions 7 fromthe spool 10 through the openings 13, the mowing machine is swungvertically by an operator during its operation to move the shifter 12with its inertia relative to the casing 5' as indicated by arrow A inFIG. 4 so that the upper projections 14 on the shifter 12 disengage fromthe projections 16 on the casing 5'. Due to the fact that the free endportions of the cutting lines 11 are being stretched outwardly under theaction of the centrifugal force, the shifter 12 is moved in a directionof arrow B until the lower projections 15 on the shifte 12 engage theprojections 17 on the cap 5 so that the cutting lines 11 are extractedfrom the spool 10 through the openings 13 by half of a predeterminedlength. Then, the shifter 12 is lifted as indicated by arrow C by theoutward force on the free end portions 7 of the cutting lines 11 so thatthe lower projections 15 on the shifter 12 disengage from theprojections 17 on the cap 5. The outward force on the free end portions7 of the cutting lines 11 also causes the shifter 12 to move forwardrelative to the casing as indicated by arrow D until the upperprojections 14 on the shifter 12 engage the projections 16 on the casing5', thereby extracting the cutting lines by the other half.

It will be seen from the foregoing that when the mowing machine isswung, the inertia on the shifter and the centrifugal force on the freeend portions of the cutting lines result in the vertical and angularmovement of the shifter 12 relative to the casing, thereby causing thecutting lines 11 to automatically extruct from their spool 10 throughthe openings 13 the predetermined length.

In the preferred embodiment of the present invention, in order toextruct the cutting lines 11 from their spool 10 a predetermined lengthon halves, the upper and lower projections are formed on the shifter 12in the opposite relation and each of the projections 17 on the cap 5 ispositioned intermediately between the two adjacent projections 16 on thecasing 5'. Alternatively, only the upper projections 14 and theprojections 16 may be formed on the shifter 12 and the casing 5',respectively.

It will be apparent from the foregoing that many other variations andmodifications may be made in structures described herein withoutdeparting from the essential concept of the present invention.

What is claimed is:
 1. A mowing machine having a cutting head comprisinga driving shaft, a casing means fixedly secured to the driving shaft forrotation therewith and having a plurality of circumferentially spacedprojections formed thereon, at least one flexible cutting line in theform of a coil wound on a spool housed in and removably fixed to thecasing means and having a free end portion, an annular inertia shifterdisposed in the casing means in a relation surrounding the coil and thespool .[.at its radial outward position.]. .Iadd.radially outwardly ofthe spool .Iaddend.for vertical and angular movements relative to thecasing means and having a plurality of circumferentially spacedprojections formed thereon and adapted to engage said projections on thecasing means during the mowing operation of the machine, said inertiashifter being provided with at least one opening through which said freeend portion of the cutting line extended radially outwardly.
 2. Themowing machine of claim 1 wherein said casing means comprises an uppercasing portion and a lower cap portion fixedly secured to one anotherand said casing means projections are located at circumferentiallyspaced portions on siad upper casing portion and said cap portion. 3.The mowing machine of claim 1 wherein said casing means includes anupper casing portion and a lower cap portion with said circumferentiallyspaced projections of said casing means being located on only said uppercasing portion and extending downwardly therefrom.
 4. The mowing machineof claim 3 wherein said circumferentially spaced projections on saidinertia shifter are on only an upper surface thereof and extend upwardlyto engage the downwardly extending projections on said upper casingportion.
 5. The mowing machine of claim 2 wherein said spool is clampedbetween said casing portion and said cap portion for rotation therewith.6. The mowing machine of claim 1 wherein said annular inertia shifterhas two openings formed in an annular wall thereof for two flexiblecutting lines. .Iadd.
 7. In a line feeding device having a housingdefining an axis of rotation, said housing being fixed to a rotatablespool having a supply of line intended to be fed therefrom and woundthereabout with a distal end of the line urged radially outwardly as anincident of rotation of the spool on said housing about said axis, theimprovement comprising:an inertia shifter releasably engaging saidhousing to be carried for rotation about said axis therewith, anddefining a through feed hole opening radially of said axis of rotationfor passing the distal end of the line outwardly therethrough, saidhousing extending axially downwardly below said inertia shifter; saidinertia shifter being movable about said axis relative to the housingand spool as an incident of disengagement of the inertia shifter fromsaid housing, and thereby permitting the outwardly urged distal end ofthe line to urge said inertia shifter circumferentially about said axisto reposition said opening progressively in the direction of unwindingof the line from said spool thereby progressively feeding the distal endof the line from said spool only while said inertia shifter isdisengaged from said housing. .Iaddend. .Iadd.8. In a line feedingdevice having a housing defining an axis of rotation, said housing beingfixed to a rotatable spool having a supply of line intended to be fedtherefrom and wound thereabout with a distal end of the line urgedradially outwardly as an incident of rotation of the spool on saidhousing about said axis, the improvement comprising: an inertia shifterreleasably engaging said housing to be carried for rotation about saidaxis therewith, and defining a through feed hole opening radially ofsaid axis of rotation for passing the distal end of the line outwardlytherethrough; means for urging the inertia shifter axially upwardly to afirst position upon the line feeding device being rotated, said inertiashifter being movable about said axis relative to the housing and spoolas an incident of movement of the inertia shifter axially downwardlyfrom said first position, and thereby permitting the outwardly urgeddistal end of the line to urge said inertia shifter circumferentiallyabout said axis to reposition said opening progressively in thedirection of unwinding of the line from said spool thereby progressivelyfeeding the distal end of the line from said spool only while saidinertia shifter is disengaged from said housing. .Iaddend. .Iadd.9. Theline feeding device of claim 8 wherein said inertia shifter isreleasably retained against circumferential displacement by a forcedeveloped by the distal end of the line extending outwardly through saidopening. .Iaddend. .Iadd.10. In a line feeding device having a housingdefining an axis of rotation, said housing being fixed to a rotatablespool having a supply of line intended to be fed therefrom and woundthereabout with a distal end of the line urged radially outwardly as anincident of rotation of the spool on said housing about said axis, theimprovement comprising:an annular inertia shifter movably carried forrotation about said axis with said housing and defining a through feedhole opening radially of said axis of rotation for passing the distalend of the line outwardly therethrough; and means for selectivelyincrementally permitting said inertia shifter to move relative to thehousing circumferentially about said axis to reposition said openingsequentially progressively in the direction of unwinding of the linefrom said spool thereby progressively incrementally feeding the distalend of the line from said spool while said spool and housing arerotating about said axis. .Iaddend. .Iadd.11. The line feeding device ofclaim 10 wherein said inertia shifter is releasably retained againstcircumferential displacement by a force developed by the distal end ofthe line extending outwardly through said opening. .Iaddend. .Iadd.12.An apparatus for controllably feeding flexible line having a free endfrom a spool having a core with a vertical axis about which the spool isintended to be rotated in a first direction, said apparatus comprising:a housing; means for fixing the housing to the spool to define a spoolassembly so that the housing follows rotation of the spool; an inertiashifter, said housing extending axially downwardly below said inertiashifter; means on the inertia shifter and spool assembly which with theinertia shifter in a first position cooperate to prevent relativerotation between the inertia shifter and spool assembly; means mountingthe inertia shifter for movement between the first position and a secondinertia shifter position in which the inertia shifter is rotatablerelative to the spool assembly; means biasing the inertia shiftertowards its first position; and means on the inertia shifter engagingthe free end portion of the line so that the line free end followsrotational movement of the inertia shifter and is extendable radiallyrelative to the spool as line is paid out from the spool, said inertiashifter, upon being moved against the biasing means and realizing thesecond position shifting rotatably relative to the spool as the spoolassembly is rotated and thereby causing said line to pay out from thecore. .Iaddend. .Iadd.13. The line feeding apparatus according to claim12 wherein said inertia shifter is movable axially upwardly relative tothe spool axis to the first position, the inertia shifter has a throughfeed hole for passing the free line end, the means engaging the free endcomprises an edge of the inertia shifter about the feed hole including adownwardly facing edge portion, said spool has a flange with a bottomsurface axially bounding a bottom portion of the core upon which theline is wound and with the inertia shifter in the first position thedownward facing edge portion is spaced axially from the flange surfaceless than the thickness of the line so that as the spool assemblyrotates the centrifugal forces on the free line end urge the inertiashifter towards its first position. .Iaddend. .Iadd.14. An apparatus forcontrollably feeding flexible line, said apparatus comprising:a housingto be fixed to a rotary drive for rotation about a first axis; a coreabout which a flexible line with a free end portion is wound in a firstdirection, said housing having a portion radially outwardly of and inaxial overlapping relationship with the core; means for fixing the coreto the housing; an inertia shifter; means on the inertia shifter andhousing which, with the inertia shifter in a first position cooperate toprevent relative rotation about the first axis between the inertiashifter and housing; means mounting the inertia shifter for movementrelative to the housing between the first position and a second inertiashifter position in which the inertia shifter is rotatable relative tothe housing about the first axis; and means on the inertia shifterengaging the free end portion of the line so that the free end portionof the line follows rotational movement of the inertia shifter and isextendable radially relative to the first axis as line is being paid outfrom the core, said inertia shifter, in said second position, shiftingrotatably relative to the housing about said first axis and therebycausing line to be controllably fed off of the core. .Iaddend. .Iadd.15.The line feeding apparatus according to claim 14 wherein the housing hasa bottom surface defining the lower extremity of the apparatus..Iaddend. .Iadd.16. The line feeding apparatus according to claim 14wherein the core has associated radially extending flanges defining aline storage space, as the housing is rotated the free end portion ofthe line is urged radially outwardly by centrifugal force and said meansengaging the free end of the line comprises a surface on the inertiashifter surrounding an aperture through which the free end portion ofthe line is passed and the axially uppermost portion of the surroundingsurface is approximately axially aligned with the bottom of the linestorage space so that the free end portion of the line urges the inertiashifter toward its first position as the spool housing assembly isrotated in the first direction. .Iaddend.